EP 217 333 B (Dow Corning Corp.; published on Sep. 2, 1992) describes xylene-soluble, resinous copolymers which contain SiO.sub.2, trimethylsiloxy and alkenyldimethylsiloxy units and are suitable for regulating separating forces with respect to adhesives. U.S. Pat. No. 4,123,604 (Dow Corning Corp., issued on Oct. 31, 1978) describes the preparation of resinous siloxane copolymers using vinyldimethylsiloxy units. Both publications have the common feature that the molecular weight of the copolymers is determined by the ratio of monomeric siloxane units to quaternary siloxane units in the molecule.